package com.hmdp.utils;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.CACHE_NULL_TTL;

@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicalExpire(String key, Object value,Long expire,TimeUnit unit){
        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(expire)));
        redisData.setData(value);
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }
    public <R,ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type,
                                         Function<ID,R> dbFallBack, Long time, TimeUnit unit){
        String key = keyPrefix + id;
        //1.从Redis查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, type);
        }
        //上面是有值的情况，下面是无值的2种情况：A：空字符串。B：null。
        if(shopJson != null){
            return null;
        }
        //4.不存在，根据id查询数据库
        R r = dbFallBack.apply(id);
        //5.不存在，返回错误
        if(r==null){
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入Redis
        this.set(key,r,time,unit);
        return r;
    }




}

